OBJECTIVE: To investigate the therapeutic effect of Epothilone D on traumatic optic neuropathy (TON) in rats. METHODS: Forty-two SD rats were randomized to receive intraperitoneal injection of 1.0 mg/kg Epothilone D or DMSO (control) every 3 days until day 28, and rat models of TON were established on the second day after the first administration. On days 3, 7, and 28, examination of flash visual evoked potentials (FVEP), immunofluorescence staining and Western blotting were performed to examine the visual pathway features, number of retinal ganglion cells (RGCs), GAP43 expression level in damaged axons, and changes of Tau and pTau-396/404 in the retina and optic nerve. RESULTS: In Epothilone D treatment group, RGC loss rate was significantly decreased by 19.12% (P=0.032) on day 3 and by 22.67% (P=0.042) on day 28 as compared with the rats in the control group, but FVEP examination failed to show physiological improvement in the visual pathway on day 28 in terms of the relative latency of N2 wave (P=0.236) and relative amplitude attenuation of P2-N2 wave (P=0.441). The total Tau content in the retina of the treatment group was significantly increased compared with that in the control group on day 3 (P < 0.001), showing a consistent change with ptau-396/404 level. In the optic nerve axons, the total Tau level in the treatment group was significantly lower than that in the control group on day 7 (P=0.002), but the changes of the total Tau and pTau-396/404 level did not show an obvious correlation. Epothilone D induced persistent expression of GAP43 in the damaged axons, detectable even on day 28 of the experiment. CONCLUSION Epothilone D treatment can protect against TON in rats by promoting the survival of injured RGCs, enhancing Tau content in the surviving RGCs, reducing Tau accumulation in injured axons, and stimulating sustained regeneration of axons.
Animals ; Disease Models, Animal ; Epothilones ; Evoked Potentials, Visual ; Nerve Regeneration/physiology* ; Optic Nerve Injuries/metabolism* ; Rats ; Rats, Sprague-Dawley ; Retinal Ganglion Cells/physiology*

Microglia are involved in the inflammatory response and retinal ganglion cell damage in glaucoma. Here, we investigated how microglia proliferate and migrate in a mouse model of chronic ocular hypertension (COH). In COH retinas, the microglial proliferation that occurred was inhibited by the P2X7 receptor (P2X7R) blocker BBG or P2X7R knockout, but not by the P2X4R blocker 5-BDBD. Treatment of primary cultured microglia with BzATP, a P2X7R agonist, mimicked the effects of cell proliferation and migration in COH retinas through the intracellular MEK/ERK signaling pathway. Transwell migration assays showed that the P2X4R agonist CTP induced microglial migration, which was completely blocked by 5-BDBD. In vivo and in vitro experiments demonstrated that ATP, released from activated Müller cells through connexin43 hemichannels, acted on P2X7R to induce microglial proliferation, and acted on P2X4R/P2X7R (mainly P2X4R) to induce microglial migration. Our results suggest that inhibiting the interaction of Müller cells and microglia may attenuate microglial proliferation and migration in glaucoma.
Adenosine Triphosphate/pharmacology* ; Animals ; Cell Proliferation ; Glaucoma/metabolism* ; Mice ; Microglia/metabolism* ; Receptors, Purinergic P2X4/metabolism* ; Receptors, Purinergic P2X7/metabolism* ; Retinal Ganglion Cells/metabolism*

OBJECTIVE: To investigate the effect of G protein-coupled receptor 17 (GPR17) on hypoxia injury in retinal ganglion cells . METHODS: CoCl (400 μmol/L) was used to induce hypoxic injury in RGC-5 cells. The expression of GPR17 and the effect of GPR17 ligands were investigated, and the role of GPR17 in hypoxia injury was further studied by transfection of RGC-5 cells with GPR17 small interfering RNA (siRNA). The cell viability was determined by MTT and the cell apoptosis rate was detected by flow cytometry analysis. The expression of GPR17 mRNA was determined with RT-PCR. RESULTS: mRNA expressions of GPR17 in RGC-5 cells with and without CoCl treatment were 0.36±0.05 and 0.26±0.08(<0.01). Compared with hypoxia without any treatment, pretreatment with GPR17 agonists (LTD, UDP, UDP-G) significantly reduced cell viability (the survival rates of cells decreased by 29.6%, 31.8% and 33.9%, all <0.01), while the effect of GPR17 antagonist (cangrelor) was the opposite (the survival rates of cells increased by 33.2%, <0.01). Transfection with GPR17 SiRNA inhibited hypoxia-induced up-expression of GPR17 mRNA (<0.01)and reduced cell apoptosis[rates of cell apoptosis were(39.73±2.06)%,(42.50±3.64)% and (24.98±2.16)% for blank control, NC siRNA and GPR17 siRNA groups, <0.01]. CONCLUSIONS GPR17 may mediate hypoxia injury in RGC-5 cells, while the knockdown of GPR17 can reduce the hypoxia injury.
Apoptosis ; Cell Hypoxia ; genetics ; Cell Line ; Cell Survival ; Cobalt ; Gene Expression Regulation ; drug effects ; Gene Knockdown Techniques ; Humans ; Hypoxia ; chemically induced ; genetics ; Receptors, G-Protein-Coupled ; genetics ; metabolism ; Retinal Ganglion Cells ; drug effects

BACKGROUNDCollapsin response mediator protein-2 (CRMP2) has been shown to be involved in ischemia/hypoxia (IH) injury. We determined whether CRMP2 modulates ischemic injury in the retinal of Ocular ischemic syndrome (OIS). This study was to explore the molecular mechanisms underlying OIS in a novel mice model.

METHODSExperiments were performed on adult male C57/BL6 mice that received bilateral internal carotid arteries ligation for 1, 2, or 4 weeks. The mice received injection of calpeptin group before occlusion for 4 weeks or not. The expression of CRMP2 in the retinal was examined by western blotting (WB) analysis and immunohistochemical analysis (IHC). The effects of ischemic injury on retinal were evaluated by fundus examination, fundus fluorescein angiography, electroretinogram, cell counting of retinal ganglion cell (RGC), and measurement of the thickness of the retina.

RESULTSThe veins dilated after chronic ischemia. In the electroretinography, the amplitudes of a- and b-waves kept diminishing in an ischemia time-dependent manner. Moreover, the tail vein-retinal circulation time prolonged in the 1- and 2-week group. In comparison, thickness of the retina decreased gradually with the ischemia time elapsed. WB analysis showed the CRMP2 and p-CRMP2 levels decreased in the 2- and 4-week groups. The results of IHC analysis were compatible with our results of WB. The loss of RGCs, decrease of the total reaction time and reduction of CRMP2 was alleviated by intravitreal injection of calpeptin.

CONCLUSIONSThese results revealed that bilateral ligation of the internal carotid artery causes retinal ischemia in mice. Moreover, CRMP2 might play a pivotal role during the ischemic injury in the retina and inhibit the cleavage of CRMP2 can ameliorate the IH injury.

Animals ; Disease Models, Animal ; Electroretinography ; Intercellular Signaling Peptides and Proteins ; genetics ; metabolism ; Ischemia ; genetics ; metabolism ; pathology ; Male ; Mice ; Mice, Inbred C57BL ; Nerve Tissue Proteins ; genetics ; metabolism ; Retinal Diseases ; genetics ; metabolism ; pathology ; Retinal Ganglion Cells ; metabolism ; pathology

The purpose of this study was to investigate the effect of inhibition of calpain on retinal ganglion cell-5 (RGC-5) necroptosis following oxygen glucose deprivation (OGD). RGC-5 cells were cultured in Dulbecco's-modified essential medium and necroptosis was induced by 8-h OGD. PI staining and flow cytometry were performed to detect RGC-5 necrosis. The calpain expression was detected by Western blotting and immunofluorescence staining. The calpain activity was tested by activity detection kit. Flow cytometry was used to detect the effect of calpain on RGC-5 necroptosis following OGD with or without N-acetyl-leucyl-leucyl-norleucinal (ALLN) pre-treatment. Western blot was used to detect the protein level of truncated apoptosis inducing factor (tAIF) in RGC-5 cells following OGD. The results showed that there was an up-regulation of the calpain expression and activity following OGD. Upon adding ALLN, the calpain activity was inhibited and tAIF was reduced following OGD along with the decreased number of RGC-5 necroptosis. In conclusion, calpain was involved in OGD-induced RGC-5 necroptosis with the increased expression of its downstream molecule tAIF.
Animals ; Apoptosis Inducing Factor ; biosynthesis ; genetics ; Calpain ; biosynthesis ; genetics ; Gene Expression Regulation ; drug effects ; Glucose ; metabolism ; Humans ; Leupeptins ; administration & dosage ; Mice ; Oxygen ; metabolism ; Retinal Ganglion Cells ; metabolism ; pathology ; Retinal Necrosis Syndrome, Acute ; genetics ; pathology

PURPOSE: Maltol (3-hydroxy-2-methyl-4-pyrone), formed by the thermal degradation of starch, is found in coffee, caramelized foods, and Korean ginseng root. This study investigated whether maltol could rescue neuroretinal cells from oxidative injury in vitro. METHODS: R28 cells, which are rat embryonic precursor neuroretinal cells, were exposed to hydrogen peroxide (H2O2, 0.0 to 1.5 mM) as an oxidative stress with or without maltol (0.0 to 1.0 mM). Cell viability was monitored with the lactate dehydrogenase assay and apoptosis was examined by the terminal deoxynucleotide transferase-mediated terminal uridine deoxynucleotidyl transferase nick end-labeling (TUNEL) method. To investigate the neuroprotective mechanism of maltol, the expression and phosphorylation of nuclear factor-kappa B (NF-kappaB), extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 were evaluated by Western immunoblot analysis. RESULTS: R28 cells exposed to H2O2 were found to have decreased viability in a dose- and time-dependent manner. However, H2O2-induced cytotoxicity was decreased with the addition of maltol. When R28 cells were exposed to 1.0 mM H2O2 for 24 hours, the cytotoxicity was 60.69 ± 5.71%. However, the cytotoxicity was reduced in the presence of 1.0 mM maltol. This H2O2-induced cytotoxicity caused apoptosis of R28 cells, characterized by DNA fragmentation. Apoptosis of oxidatively-stressed R28 cells with 1.0 mM H2O2 was decreased with 1.0 mM maltol, as determined by the TUNEL method. Western blot analysis showed that treatment with maltol reduced phosphorylation of NF-kappaB, ERK, and JNK, but not p38. The neuroprotective effects of maltol seemed to be related to attenuated expression of NF-kappaB, ERK, and JNK. CONCLUSIONS: Maltol not only increased cell viability but also attenuated DNA fragmentation. The results obtained here show that maltol has neuroprotective effects against hypoxia-induced neuroretinal cell damage in R28 cells, and its effects may act through the NF-kappaB and mitogen-activated protein kinase signaling pathways.
Animals ; *Apoptosis ; Blotting, Western ; Cell Survival ; Cells, Cultured ; Disease Models, Animal ; Flavoring Agents/pharmacology ; In Situ Nick-End Labeling ; Oxidative Stress/*drug effects ; Pyrones/*pharmacology ; Rats ; Retinal Ganglion Cells/drug effects/metabolism/*pathology

BACKGROUNDCurrently, no medicine is available that can prevent or treat neural damage associated with optic nerve injury. Minocycline is recently reported to have a neuroprotective function. The aims of this study were to exarmine the neuroprotective effect of minocycline on retinal ganglion cells (RGCs) and determine its underlying mechanisms, using a mouse model of optic nerve crush (ONC).

METHODSONC was performed in the left eye of adult male mice, and the mice were randomly divided into minocycline-treated group and saline-treated control group. The mice without receiving ONC injury were used as positive controls. RGC densities were assessed in retinal whole mounts with immunofluorescence labeling of βIII-tubulin. Transmission electron microscopy was used to detect RGC morphologies, and Western blotting and real-time PCR were applied to investigate the expression of autophagy markers LC3-I, LC3-II, and transcriptional factors nuclear factor-κB1 (NF-κB1), NF-κB2.

RESULTSIn the early stage after ONC (at Days 4 and 7), the density of RGCs in the minocycline-treated group was higher than that of the saline-treated group. Electron micrographs showed that minocycline prevented nuclei and mitochondria injuries at Day 4. Western blotting analysis demonstrated that the conversion of LC3-I to LC3-II was reduced in the minocycline-treated group at Days 4 and 7, which meant autophagy process was inhibited by minocycline. In addition, the gene expression of NF-κB2 was upregulated by minocycline at Day 4.

CONCLUSIONThe neuroprotective effect of minocycline is generated in the early stage after ONC in mice, partly through delaying autophagy process and regulating NF-κB2 pathway.

Animals ; Autophagy ; drug effects ; Male ; Mice ; Minocycline ; therapeutic use ; NF-kappa B p52 Subunit ; metabolism ; Optic Nerve Injuries ; drug therapy ; metabolism ; Retinal Ganglion Cells ; drug effects ; metabolism

PURPOSE: To assess whether the expression of heat shock protein 72 (Hsp72) protects rat retinal ganglion cells (RGC-5) from apoptotic cell death. METHODS: Hsp72 expression in RGC-5 cells transduced with replication-deficient recombinant adenovirus was analyzed by Western blot analysis and immunofluorescence. The effect of Hsp72 expression on etoposide-induced apoptotic cell death was examined by microscopic analysis and confirmed by cell proliferation assay. RESULTS: Western blot analysis and immunofluorescence clearly showed adenovirus-mediated Hsp72 expression in RGC-5 cells. Treatment with etoposide resulted in the death of a proportion of the cells by apoptosis. However, this apoptotic cell death was significantly reduced in cells expressing Hsp72, with the reduction in cell death correlating to the level of Hsp72 expression. CONCLUSIONS: Over-expression of Hsp72 alone is sufficient to rescue neuronal cells from apoptotic cell death, suggesting that fine-tuning its expression may be an effective neuroprotective approach in retinal degenerative disease.
Animals ; Blotting, Western ; Cell Death/*genetics ; Cell Survival ; Cells, Cultured ; DNA/*genetics ; Disease Models, Animal ; Etoposide/toxicity ; *Gene Expression Regulation ; HSP72 Heat-Shock Proteins/biosynthesis/*genetics ; Immunohistochemistry ; Rats ; Retinal Degeneration/*genetics/metabolism/pathology ; Retinal Ganglion Cells/drug effects/*metabolism/pathology

OBJECTIVETo gain insight into the potential mechanism of mitochondria dysfunction in pathogenesis, progression and therapeutic management of glaucoma.

DATA SOURCESThe data used in this review were mainly published in English from 2000 to present obtained from PubMed. The search terms were "mitochondria", "glaucoma" and "trabecular meshwork" or "retinal ganglion cells".

STUDY SELECTIONArticles studying the mitochondria-related pathologic mechanism and treatment of glaucoma were selected and reviewed.

RESULTSMitochondrial dysfunction or injury was demonstrated in different eye tissue of glaucoma. A variety of potential injuries (light, toxic materials, oxidative injury, mechanical stress, aging, etc.) and the inherent DNA defects are deemed to cause mitochondrial structural and functional destruction in trabecular meshwork cells, retinal ganglion cells, etc. of glaucoma. In addition, various new experimental and therapeutic interventions were used to preserve mitochondrial function, which may be useful for protecting against optic nerve degeneration or reducing the death of retinal ganglion cells in glaucoma.

CONCLUSIONSMitochondria play an important role in the pathogenesis of glaucoma, various strategies targeting mitochondrial protection might provide a promising way to delay the onset of glaucoma or protect RGCs against glaucomatous damage.

Glaucoma ; metabolism ; pathology ; Humans ; Mitochondria ; metabolism ; Retinal Ganglion Cells ; metabolism ; Trabecular Meshwork ; metabolism

One common feature of glaucoma, optic neuritis and some other optic nerve diseases is sustained and irreversible apoptosis of retinal ganglion cells (RGCs). Ginkgolide B is believed to protect neurons in brain and contribute to neurite outgrowth and synapse formation. The aim of the present study was to explore the effects of Ginkgo biloba extract (EGB761) and ginkgolide B on axonal growth of RCGs. Retina explants were cultured in three-dimensional tissue culture system, and the number and length of neurites were analyzed. Immunohistochemistry staining was performed to confirm that the neurite observed was axon of RGCs. TUNEL and activated caspase-3 staining were also applied to observe RGCs apoptosis. The result shows that neurites of RGCs treated with EGB761 or ginkgolide B were more and longer than those in control. The neurite is proved to be the axon of RGCs by immunostaining. Furthermore, compared with control group, RGCs treated with ginkgolide B showed decreased cellular apoptosis and inhibited caspase-3 activation. These results suggest ginkgolide B can promote RGCs axon growth by protecting RGCs against apoptosis.
Animals ; Apoptosis ; Axons ; drug effects ; Caspase 3 ; metabolism ; Ginkgolides ; pharmacology ; Lactones ; pharmacology ; Neurites ; drug effects ; Organ Culture Techniques ; Plant Extracts ; pharmacology ; Rats ; Retina ; Retinal Ganglion Cells ; cytology ; drug effects